EP1881173A1 - Diffusor for internal combustion engine and engine with such a diffusor - Google Patents

Abstract

The multi-diffuser (1) has a housing (4) expanding along a longitudinal axis (L) from a diffuser inlet (2) to a diffuser outlet (3), and a diffuser insert (5) arranged within the housing. The diffuser inlet is connected with an output (6) of an exhaust gas turbo-charger (7) and the diffuser outlet is connected with a charge-air cooler (8) of a reciprocating internal combustion engine, such that fresh air (9) is introduced into the cooler from the turbocharger by the diffuser. The diffuser is formed asymmetrical relative to the longitudinal axis.

Description

The invention relates to a multi-diffuser for a reciprocating internal combustion engine, in particular for a two-stroke large diesel engine, and a reciprocating internal combustion engine with an inventive multi-diffuser according to the preamble of the independent claims.

To increase the performance of reciprocating internal combustion engines, such as large diesel engines for ships or stationary systems for generating electrical energy, the fresh air is introduced by a Aufladegruppe, which is usually designed as an exhaust gas turbocharger, under increased pressure in the combustion chamber of a cylinder after a combustion cycle. In this case, a part of the thermal energy of the exhaust gases can be exploited, leaving the combustion chamber of the cylinder after the combustion cycle. For this purpose, the hot exhaust gases are supplied by opening an exhaust valve from the combustion chamber of the cylinder of Aufladegruppe. The charging group consists essentially of a turbine, which passes through the hot exhaust gases entering under pressure in the charging group is driven. The turbine in turn drives an impeller, whereby fresh air is sucked in and compressed. The turbine with impeller as a compressor, an arrangement which is often referred to simply as a turbocharger and especially, but not only, designed in the case of two-stroke large diesel engines as a centrifugal compressor, a so-called diffuser, a charge air cooler with a water separator and an inlet receiver downstream of where from the compressed fresh air, also referred to as charge air or scavenging air, is finally fed into the individual combustion chambers of the cylinder of the large diesel engine. The use of such a charging group can thus increase the supply of fresh air and increase the efficiency of the combustion process in the combustion chamber of the cylinder.

In the case of large diesel engines, depending on the type, the supply of air takes place at different points on the cylinder. For example, in longitudinally-flushed two-stroke engines, the air is introduced into the combustion chamber of the cylinder via scavenging slots which are arranged in the running surface in the lower region of the cylinder. In four-stroke engines, the charge air is usually introduced via one or more intake valves, which are arranged in the cylinder cover into the combustion chamber of the cylinder. In this case, two-stroke engines are quite well known, which are equipped instead of scavenging slots in the lower part of the cylinder with intake valves in the cylinder cover.

A central importance for the fresh air supply of the cylinder comes to the above-mentioned diffuser. As is well known to those skilled in the art, a diffuser is essentially a funnel-shaped extension of a flow channel. It generally serves to delay, that is, to reduce the flow velocity of the flow, so that according to the known law of Bernoulli an increase in pressure is achieved. To be in the subsonic flow, like them usually occur in diffusers of reciprocating internal combustion engines in operating condition, to avoid separation of the flow in the diffuser from the diffuser inner wall and the formation of vortices, resulting in a reduction in efficiency, the double opening angle of 2θ of the diffuser should be about 16 ° 8 ° do not exceed. That is, the opening angle that forms a diffuser wall with a longitudinal axis of the diffuser should be as small as possible about 8 °, preferably less than 4 °. It is known, downstream subsonic fans in particular with the use of centrifugal fans, centrifugal pumps, jet pumps, centrifugal compressors, etc., where it is necessary to recover energy through effective conversion of kinetic energy in pressure.

The above-mentioned limitation of the opening angle has some significant disadvantages. Thus, in the direction of the longitudinal axis of the diffuser, a certain size can not be exceeded, if a predetermined efficiency is to be achieved. That is, the diffuser must have a certain minimum length depending on the application and the efficiency to be achieved, which of course is very disadvantageous in confined spaces, e.g. when there is not enough space between the turbocharger and intercooler connected to the diffuser in a two-stroke large diesel engine.

On the other hand, this means that if a certain length of the diffuser may not be exceeded due to geometric boundary conditions, the conversion of kinetic energy of the incoming fresh air in pressure energy is only possible to a limited extent, resulting in a reduction in the efficiency of the diffuser.

In certain cases, these problems can be solved by the use of so-called multi-diffusers. A multidiffuser is understood by the person skilled in the art to be the concentric nesting of several diffusers, thus forming the multi-diffuser. That means it will be two or a plurality of hollow bodies, for example in the form of different sized cones with the same or different opening angles, concentrically nested. The fact that, for example, the fresh air is then guided in several concentric conical chambers from the entrance of the diffuser to the outlet of the diffuser, the outer jacket of the multi-diffuser can have a significantly larger opening angle than 2θ = 16 °, without the flow on the surfaces of the nested Tapering of the multi-diffuser tears off. As a result, in spite of the shortened length of the multi-diffuser compared to a conventional diffuser, in certain cases still a sufficient efficiency, or even improved compared to a conventional diffuser efficiency can be achieved.

In the DE 197 10 408 A1 An embodiment of such a multi-diffuser for use in a reciprocating internal combustion engine is discussed.

However, it has been shown that the known multi-diffusers are in practice for use in reciprocating internal combustion engines, especially those in which the Aufladegruppe, so the turbocharger is designed as a radial compressor, are poorly suited, because it also in the multi-diffusers to separations of Flow with the concomitant harmful effects of the resulting turbulence, whereby the efficiency is again significantly reduced, so that the use of the known multi-diffusers in reciprocating internal combustion engines, especially in two-stroke large diesel engines ultimately not worth it and therefore, for example have not yet been used in Wärtsilä large-bore engines.

On the other hand, there is an urgent need mainly for cost reasons, as well as structural geometric reasons, the overall length of the diffusers in reciprocating internal combustion engines, especially in two-stroke To reduce large diesel engines and / or at the same time to increase the efficiency in comparison to the conventionally used diffusers.

The object of the invention is therefore to propose an improved diffuser for a reciprocating internal combustion engine, in particular two-stroke large diesel engine, which has a significantly reduced overall length compared to the known diffusers, preferably additionally has a higher efficiency than the diffusers previously used in the prior art or at the same length as the known diffusers has a significantly improved efficiency. Another object of the invention is to bring a reciprocating internal combustion engine, in particular two-stroke large diesel engine with an improved diffuser in proposal.

The objects of the invention solving these objects are characterized by the features of the independent claims.

The dependent claims relate to particularly advantageous embodiments of the invention.

The invention thus relates to a multi-diffuser for a reciprocating internal combustion engine, in particular two-stroke large diesel engine, wherein the multi-diffuser comprises a diffuser housing extending from a diffuser inlet to a diffuser exit along a longitudinal axis with a diffuser insert disposed in the interior of the diffuser housing. The diffuser inlet can be connected to an outlet of an exhaust gas turbocharger and the diffuser outlet to a charge air cooler of the reciprocating internal combustion engine, so that in the operating state of the reciprocating internal combustion engine from the exhaust gas turbocharger fresh air via the multi-diffuser in the intercooler can be introduced. According to the invention, the multi-diffuser is designed asymmetrically with respect to the longitudinal axis.

It has been found that the profile of the velocity distribution of the fresh air flowing out of the turbocharger over the cross section of the outlet of the exhaust gas turbocharger and thus, of course, over the cross section of the diffuser input in no way has a highly symmetric block-like structure. This means that the velocity vectors of the fresh air flowing out of the exhaust-gas turbocharger are by no means constant over the cross-sectional area of the outlet of the exhaust gas turbocharger, but the velocity profile of the velocity vectors of the exiting fresh air have a characteristic asymmetry due to the structure of the exhaust-gas turbocharger.

If the exhaust gas turbocharger is charging side, e.g. designed as a radial compressor, whose basic structure and operation has long been well known to those skilled in the art, it has been found that at the output of the compressor of the exhaust gas turbocharger, for example in the region of an inner radius at the inner edge of the cross-sectional area of the exhaust gas turbocharger output, the speed and / or direction of the outflowing gas is significantly different than at the outer edge of the exit. Considered over the entire cross-sectional area at the outlet of the exhaust gas turbocharger thus results in a non-rotationally symmetric velocity profile of the fresh air flowing into the diffuser, ie an asymmetric velocity profile, which is predetermined by the structure of the centrifugal compressor or at least co-determined.

That is the reason why conventional symmetrical multidiffusors, as they are used in the DE 197 10 408 A1 not show the desired degree of improvement in terms of efficiency and shortening of the length of the multi-diffuser. Namely, since the symmetry of the velocity profile of the air flowing from the exhaust gas turbocharger into the symmetric multi-diffuser is not compatible with the high symmetry of the known multi-diffuser, at least in certain areas of the multi-diffuser for tearing off the flowing fresh air, thus to turbulence and a significant deterioration in efficiency.

This asymmetry in the velocity profile of the fresh air entering the diffuser is taken into account by the multi-diffuser of the present invention in that the multi-diffuser according to the invention is designed asymmetrically with respect to its longitudinal axis. In this case, the construction of the multi-diffuser according to the invention is adapted in the specific case to the velocity profile which the exhaust-gas turbocharger delivers at its outlet and thus at the diffuser inlet.

This prevents that in the inventive multi-diffuser, the flow breaks off in certain surface areas within the multi-diffuser and the efficiency is deteriorated.

In a preferred embodiment of a multi-diffuser according to the invention, at least one first diffuser insert is designed as a hollow body which widens in the direction of the diffuser exit, in particular in the form of a straight or not straight cone. For example, if only such a diffuser insert is provided, then this is preferably formed asymmetrically with respect to the longitudinal axis of the diffuser housing in the diffuser housing. This can be done, inter alia, that the diffuser insert itself is not a circle symmetrical cone and / or a longitudinal axis of the diffuser insert is not parallel to the longitudinal axis of the diffuser housing and / or is not identical to this. Of course, it is also possible that the diffuser housing itself is not symmetrical. The person skilled in the art will readily understand how to use these and other possibilities for producing the asymmetry of a multi-diffuser according to the invention, even if more than one diffuser insert is present, appropriately and / or combined to adapt the structure of the mutli-diffuser to the velocity profile of the incoming fresh air.

In this case, a diffuser insert designated as a second diffuser insert may well be provided which is designed as a compact body which widens in the direction of the diffuser exit, in particular in the form of a straight or not straight compact cone. The fresh air can thus not flow through the second diffuser insert, but only flows past the outer surface. It is understood that in a multi-diffuser according to the invention in the diffuser housing, e.g. only a second diffuser insert and no further diffuser insert can be provided or the second diffuser insert can be combined with other diffuser inserts.

In this case, in a specific embodiment, the symmetry adjustment of the multi-diffuser to the velocity profile of the incoming fresh air can also be achieved by the installation of a third diffuser insert, which is designed in the form of a baffle, which is therefore not a compact cone or cone open on the input side and output side.

It is understood that all embodiments of possible diffuser inserts, as described or suggested in the context of the present application, can be provided either alone or in all suitable combinations in a multi-diffuser according to the invention.

In a particularly important embodiment for practice, a housing cross-section of the diffuser housing and / or an insert cross-section of the diffuser insert is designed as a cross-sectional area which increases in the direction of the diffuser exit.

The housing cross-section and / or the insert cross-section, can e.g. be formed circular and / or elliptical and / or in the form of a regular or irregular polygon, in particular in the form of a triangle or a quadrangle or a pentagon.

The diffuser housing and / or the diffuser insert preferably extends at a constant opening angle and / or continuously changing opening angle and / or under a discontinuously changing opening angle with respect to the longitudinal axis of the multi-diffuser.

In this case, the constant opening angle and / or the constantly changing opening angle and / or the discontinuously changing opening angle may be a function of a polar angle measured perpendicular to the longitudinal axis.

In an important design for the practice, as already mentioned, at least one diffuser insert and / or the diffuser housing is arranged asymmetrically with respect to the longitudinal axis of the diffuser housing.

To further influence the direction of the flow of fresh air in the multidifusor the diffuser housing and / or the diffuser insert may comprise a guide element, in particular a spiral-like guide element, in particular an arrangement with a guide vane, wherein the guide element is preferably arranged and configured such that a circumferential flow of can be deflected in the operating state from the exhaust gas turbocharger fresh air, in particular in an axial flow is deflected.

In a particularly simple embodiment of an inventive multi-diffuser exactly one diffuser insert is provided.

The necessary symmetry adjustment can also be accomplished by extending the multi-diffuser from the diffuser inlet to the diffuser exit as a curved multi-diffuser along a curved longitudinal axis.

It goes without saying that the exemplary embodiments described in this application are to be understood only as examples and in particular also all suitable combinations which are not described in detail are covered by the invention.

Moreover, the invention relates to a reciprocating internal combustion engine, in particular two-stroke large diesel engine with a multi-diffuser as described above or below with reference to the drawing.

Fig. 1

Schematisch den prinzipiellen Aufbau eines Abgasturbolader Systems;

Fig. 2

ein Radialverdichter als Abgasturbolader mit Geschwindigkeitsprofil der austretenden Frischluft;

Fig. 3

ein erstes Ausführungsbeispiel eines erfindungsgemässen Multidiffusors mit hohlkegelförmigem Diffusoreinsatz;

Fig. 4

ein zweites Ausführungsbeispiel eines erfindungsgemässen Multidiffusors gemäss Fig. 3 mit einem kompakten Diffusoreinsatz;

Fig. 5

ein Querschnitt durch einen Multidiffusor mit zwei asymmetrisch angeordneten Diffusoreinsätzen;

Fig. 6

ein Querschnitt durch einen Multidiffusor mit zwei asymmetrisch ausgebildeten Diffusoreinsätzen;

Fig. 7

ein Längsschnitt durch einen Multidiffusor mit sich stetig veränderndem Öffnungswinkel des Diffusorgehäuses;

Fig. 8

eine perspektivische Darstellung des Diffusorgehäuses der Fig. 7 mit veränderlichem Öffnungswinkel in Umfangsrichtung;

Fig. 9

ein erfindungsgemässer Multidiffusor mit gekrümmter Längsachse;

Fig. 10

ein erstes Ausführungsbeispiel eines erfindungsgemässen Multidiffusors mit Leitblechen;

Fig. 11

ein zweites Ausführungsbeispiel eines erfindungsgemässen Multidiffusors mit Leitblechen;

Fig. 12

ein Querschnitt eines Mutidiffusors mit spiralförmigem Leitelement;

Fig. 13

eine perspektivische Darstellung eines anderen Ausführungsbeispiels mit Leitbelementen.

The invention will be explained in more detail below with reference to the schematic drawing. Show it:

Fig. 1

Schematically the basic structure of an exhaust gas turbocharger system;

Fig. 2

a radial compressor as exhaust gas turbocharger with velocity profile of the exiting fresh air;

Fig. 3

A first embodiment of an inventive multi-diffuser with hollow cone-shaped diffuser insert;

Fig. 4

a second embodiment of a multi-diffuser according to the invention according to FIG. 3 with a compact diffuser insert;

Fig. 5

a cross section through a multi-diffuser with two asymmetrically arranged diffuser inserts;

Fig. 6

a cross-section through a multi-diffuser with two asymmetrically designed diffuser inserts;

Fig. 7

a longitudinal section through a multi-diffuser with constantly changing opening angle of the diffuser housing;

Fig. 8

a perspective view of the diffuser housing of Figure 7 with variable opening angle in the circumferential direction.

Fig. 9

a multi-diffuser according to the invention with a curved longitudinal axis;

Fig. 10

A first embodiment of an inventive multi-diffuser with baffles;

Fig. 11

A second embodiment of an inventive multi-diffuser with baffles;

Fig. 12

a cross-section of a helical vane helical diffuser diffuser;

Fig. 13

a perspective view of another embodiment with Leitbelementen.

Fig. 1 shows a schematic representation to explain the interaction of the different components of the basic structure of an exhaust gas turbocharger system of a large diesel engine, which is designed as a two-stroke large diesel engine with longitudinal flush and equipped with an inventive multi-diffuser, which is hereinafter referred to collectively by the reference numeral 1 ,

The large diesel engine usually comprises a plurality of cylinders 1000 with an exhaust valve 1001 arranged in a cylinder cover, in which cylinder 1000 a piston 1002 between a bottom dead center UT and a top dead center OT is arranged back and forth along a running surface. The cylinder 1000 with cylinder cover and the piston 1002 limit in known manner a combustion chamber of the cylinder 1000. In the lower region of the cylinder 1000 several purge air openings 1003 are provided, which are designed as flushing slots 1003. Depending on the position of the piston 1002, the flushing slots 1003 are covered or released by this. Due to the scavenging air openings 1003, the fresh air 9 designated as scavenging air 9 can flow into the combustion chamber of the cylinder 1000.

Due to the exhaust valve 1001 arranged in the cylinder cover, the exhaust gases 1004 formed during the combustion flow through an exhaust pipe 1005, which adjoins the exhaust valve 1001, into an exhaust gas turbocharger 7.

The exhaust gas turbocharger 7 comprises, as essential components in a manner known per se, a compressor 71 with compressor impeller 711 for compressing air 9, and a turbine 72 with a turbine impeller 721 for driving the compressor impeller 711, which is operatively connected to the turbine impeller 721 by a shaft in a known manner connected is. The turbine 72 and the compressor 71 are arranged in a housing and form an exhaust-gas turbocharger 7, which in the present case is designed as a radial compressor 72 on the compressor side. The turbine 72 is driven in a known manner by the incoming hot exhaust gases 1004 from the combustion chamber of the cylinder 1000.

For charging the combustion chamber of the cylinder 1000 with scavenging air 9, fresh air 9 is sucked in through the compressor impeller 711 via an intake manifold and compressed in the exhaust gas turbocharger 7. From the exhaust gas turbocharger 7, the compressed fresh air 9 passes through a downstream multidiffusor 1 and a charge air cooler 8 via a pressure line into an inlet receiver 1006, from which the compressed fresh air 9 finally as scavenging air 9 through the scavenging slots 1003 under increased pressure in the combustion chamber of the cylinder 1000 arrives.

In Fig. 2, constructed as a centrifugal compressor exhaust gas turbocharger 7 is shown in somewhat greater detail. Radial compressors are known per se. These are compressors with an impeller flow, which have a radial velocity component except for the circumferential component for working transmission.

The air is thus compressed by an impeller in the centrifugal compressor and conveyed at a certain speed V via the outlet 6 of the exhaust gas turbocharger 7 via the diffuser inlet 2 into the diffuser 1.

In this case, the velocity V of the exiting fresh air 9 is dependent on the cross-sectional coordinate X and thus on the cross-sectional area 400 over a certain cross-sectional coordinate X over the insert cross section 500 of the output 6 of the exhaust gas turbocharger 7, and thus over the cross-sectional coordinate X over the housing cross-section 400. 500 not constant. That is, the velocities V of the fresh air 9 entering the multi-diffuser 1 from the exhaust-gas turbocharger 7 at a certain coordinate X obeys a velocity profile P which is a function of at least one coordinate X of the cross-sectional area 400, 500.

This asymmetry in the velocity profile P of the fresh air 9 emerging from the exhaust-gas turbocharger 7 is taken into account by the asymmetrical design of the multi-diffuser 1 according to the invention, as is illustrated schematically in FIG. 3, for example. In the example of FIG. 3, fresh air 9 is introduced from the exhaust-gas turbocharger 7 via the diffuser inlet 2 into a multi-diffuser 1 according to the invention. In the multi-diffuser 1, the velocity of the incoming fresh air 9 is reduced in a manner known per se, whereby according to the Benoulli law an increase in pressure of the fresh air 9 is achieved, which thus enters the charge air cooler 8 under increased pressure. In this case, the multi-diffuser 1 according to the invention of FIG. 3 comprises exactly one diffuser insert 5, 51 in the form of a non-straight cone 51 which widens in the direction of the diffuser outlet 3. The diffuser housing 4, like the diffuser insert 51, is asymmetrical with respect to FIG formed the longitudinal axis L of the multi-diffuser 1, whereby the asymmetric shape of the velocity profile P of the velocity distribution of the incoming fresh air 9 is optimally taken into account, so that in the inventive multi-diffuser 1 a high Efficiency can be achieved because the flow of fresh air 9 in the multi-diffuser 1 does not rupture, although the multi-diffuser 1 of Fig. 3 has a large opening angle and has a relatively short length.

FIG. 4 shows a second exemplary embodiment of a multi-diffuser according to the invention according to FIG. 3 with a compact diffuser insert 5, 52. The arrangement shown in Fig. 4 corresponds substantially to the already described in detail arrangement of Fig. 3, wherein in Fig. 4, the diffuser insert 5, 52 but no expanding hollow body 51 in the form of a non-straight cone 51, as in Fig. 3rd but is a compact body 52 expanding toward the diffuser exit 3, which is configured in the form of a non-straight compact cone 52 so that the fresh air 9 can only flow around the compact cone 52 outside and not through the compact cone 52 therethrough.

Whether a compact diffuser insert 52 or a hollow diffuser insert 51 is used depends inter alia on the specific shape of the velocity profile P of the velocity distribution of the incoming fresh air 9 in the multi-diffuser 1 and / or by other boundary conditions, such as the special design of the exhaust gas turbocharger 7 and / or the intercooler 8 and / or by other boundary conditions, such as the requirements that are to be made to size and shape of the multi-diffuser 1 itself determined.

The representation of FIG. 5 shows a cross section through a multi-diffuser 1 with two asymmetrically arranged diffuser inserts 5. The diffuser housing 4 of the multi-diffuser 1 is formed asymmetrically with respect to the longitudinal axis L of the multi-diffuser 1 even in the form of an ellipse. In addition, the two diffuser inserts 5, 51, which in the exemplary embodiment of FIG. 5 are designed as hollow straight cones 5, 51 widening in the direction of the diffuser exit 3, which is not explicitly illustrated in FIG. 5, arranged asymmetrically with respect to the longitudinal axis L of Mutidiffusors 1 in the diffuser housing 4.

FIG. 6 shows a cross section through a further exemplary embodiment of a multi-diffuser 1 with two asymmetrically designed diffuser inserts 5. In the example of FIG. 6, analogous to the example of FIG. 5, the diffuser housing 4 is designed in the form of an ellipse, wherein the two diffuser inserts 5 are formed as hollow elliptical diffuser inserts 51. That is, the asymmetry of the multi-diffuser 1 with respect to the longitudinal axis L is established by the asymmetrical shape of the diffuser housing 4 and diffuser inserts 5, 51.

In a preferred exemplary embodiment, a wall of the diffuser insert 5 can also be perforated, that is to say provided with bores or openings, so that the flow in the multi-diffuser 1 can be advantageously influenced in a suitable manner, depending on the geometry and / or velocity profile P of the incoming fresh air 9 is.

In Fig. 7 is a longitudinal section through a multi-diffuser 1 with continuously changing opening angle α _{2 of} the diffuser housing 4 is shown, wherein Fig. 8 shows the embodiment of Fig. 7 again in a perspective view.

The multi-diffuser 1 according to FIG. 7 and FIG. 8 has exactly one diffuser insert 5, which is designed as a hollow cone 51 extending in the direction of the diffuser outlet 3. For reasons of clarity, only the diffuser housing 4 is shown in FIG. 8, and the diffuser insert 5, 51 is not visible.

FIG. 7 clearly shows how the opening winding α _{2 of} the diffuser housing 4 changes continuously in the direction of the longitudinal axis L, by the opening angle α ₂ from the diffuser inlet 2 to the diffuser outlet 3 is steadily smaller, while the opening angle α _{1 of} the diffuser insert 5, 51 remains constant along the longitudinal axis L.

In addition, the constantly changing opening angle α _{2 is} a function of a polar angle φ measured perpendicular to the longitudinal axis L, as a result of which inter alia the asymmetry of the multi-diffuser 1 according to the invention is determined. Fig. 7 and Fig. 8 is made.

In Fig. 9, a further embodiment of the present invention is shown, wherein the diffuser insert 5 of the multi-diffuser 1 has a curved longitudinal axis L, whereby the asymmetry in the profile P of the velocity distribution of the fresh air 9 flowing into the multidiffuser 1 also advantageous for increasing the efficiency of can take into account multi-diffuser 1 according to the invention.

FIGS. 10 and 11 show two exemplary embodiments of a multi-diffuser 1 according to the invention with baffles 5, 53. The diffuser insert 5, 53 of the multi-diffusers 1 according to FIGS. 10 and 11 are no hollow bodies extending in the direction of the diffuser exit 3 5, 51, but individual baffles 53, which are provided with respect to the longitudinal axis L asymmetrically in the diffuser housing 4 of the multi-diffuser 1.

12 shows a cross-section of a muti-diffuser 1 according to the invention with a spiral guide element 10, wherein the helical guide element 10 is arranged and configured in such a way that a circumferential flow of the fresh air 9 exiting from the exhaust-gas turbocharger 7 in the operating state can be deflected into an axial flow.

Finally, FIG. 13 shows a perspective view of another exemplary embodiment of a multi-diffuser 1 according to the invention with guide elements 10, wherein the guide elements 10 likewise deflect the incoming fresh air 9 in an advantageous manner, and e.g. As schematically indicated in FIG. 13, a velocity component of the incoming fresh air 9 running in the circumferential direction of the multidiffuser 1 is converted into an axial component, so that the fresh air 9 flowing out of the multidiffuser 1 has essentially only one axial velocity component. In the embodiment of FIG. 13, the guide elements 10 also serve to fasten the diffuser insert 5 in the diffuser housing 4 or to stabilize the diffuser insert 5 in the diffuser housing 4, idem the guide elements 10 both with an outer wall of the diffuser insert 5, and with an inner wall the diffuser housing 4 connected, for example welded or screwed or otherwise suitably fixed.

Thus, for the first time a multi-diffuser for reciprocating internal combustion engines, in particular for two-stroke large diesel engines available in which even in strongly asymmetric velocity profile of the incoming fresh air, the flow does not tear inside and thus forms no vortex. This is the first time a multi-diffuser available, with the significantly larger opening angle can be achieved, which thus allows significantly reduced lengths, while no compromise on the efficiency compared to conventional diffusers or the known symmetric Mulitdiffusoren must be accepted. If the overall length does not play a decisive role can be achieved while maintaining the length of conventional diffusers or multi-diffusers by the inventive multi-diffuser a significant increase in efficiency.

Claims (13)

A multi-diffuser for a reciprocating internal combustion engine, in particular a two-stroke large diesel engine, the multi-diffuser comprising a diffuser housing (4) expanding from a diffuser inlet (2) to a diffuser exit (3) along a longitudinal axis (L) with a diffuser insert (5) disposed in the interior of the diffuser housing (4) , 51, 52, 53), and the diffuser inlet (2) with an outlet (6) of an exhaust gas turbocharger (7) and the diffuser outlet (3) with a charge air cooler (8) of the reciprocating internal combustion engine is connectable, so that in the operating state of the reciprocating internal combustion engine the exhaust gas turbocharger (7) fresh air (9) via the multi-diffuser in the intercooler (8) can be introduced, characterized in that the multi-diffuser is designed asymmetrically with respect to the longitudinal axis (L). A multi-diffuser according to claim 1, wherein at least one first diffuser insert (51) is designed as a hollow body (51) which widens in the direction of the diffuser exit (3), in particular in the form of a straight or non-straight cone (51). Multidiffusor according to one of claims 1 or 2, wherein a second diffuser insert (52) as a towards the diffuser exit (3) expanding compact body (52), in particular in the form of a straight or not straight compact cone (52) is configured. Multi-diffuser according to one of the preceding claims, wherein a third diffuser insert (53) in the form of a guide plate (53) is formed. Multidiffusor according to one of the preceding claims, wherein a housing cross section (400) of the diffuser housing (4) and / or an insert cross section (500) of the diffuser insert (5), as in the direction of diffuser exit (3) increasing cross-sectional area (400, 500) is formed , Multidiffusor according to one of the preceding claims, wherein the housing cross-section (400) and / or the insert cross-section (500), circular and / or elliptical and / or in the form of a regular or irregular polygon, in particular in the form of a triangle or a quadrangle or a pentagon is. Multidiffusor according to one of the preceding claims, wherein the diffuser housing (4) and / or a diffuser insert (5) at a constant opening angle (α ₁ ) and / or a continuously changing opening angle (α ₂ ) and / or under a discontinuously changing Opening angle with respect to the longitudinal axis (L) extends. Multidiffusor according to one of the preceding claims, wherein the constant opening angle (α ₁ ) and / or the continuously changing opening angle (α ₂ ) and / or the discontinuously changing opening angle is a function of a perpendicular to the longitudinal axis (L) measured polar angle (φ) is. Multi-diffuser according to one of the preceding claims, wherein at least one diffuser insert (5) and / or the diffuser housing (4) with respect to the longitudinal axis (L) of the diffuser housing (4) is arranged asymmetrically. Multidiffusor according to one of the preceding claims, wherein the diffuser housing (4) and / or a diffuser insert (5) comprises a guide element (10), in particular a spiral-like guide element (10), in particular an arrangement with a guide blade (10), wherein the guide element (10) is preferably arranged and configured such that a circumferential flow of the exiting in the operating state of the exhaust gas turbocharger fresh air (9) is deflected, in particular in an axial flow is deflected. Multi-diffuser according to one of the preceding claims, wherein exactly one diffuser insert (5) is provided. A multi-diffuser according to any one of the preceding claims, wherein the multi-diffuser extends from the diffuser inlet (2) to the diffuser exit (3) as a curved multi-diffuser along a curved longitudinal axis (L). Reciprocating internal combustion engine, in particular two-stroke large diesel engine with a multi-diffuser (1) according to one of the preceding claims.

Images